In many applications, an amplifier may be used to drive a capacitive load. An example of a capacitive load is a piezoelectric transducer. A piezoelectric transducer may have many uses, including in surface audio applications, wherein a piezoelectric actuator is mechanically coupled to a surface such as the screen of a smartphone, tablet, personal computer, or other device. The vibrational transducer may, in response to an input signal received by the vibrational transducer, generate vibrational energy to vibrate the surface to generate sound.
It is known that impedance of a capacitive load monotonically decreases with a frequency of a signal driven to a capacitive load, meaning that maintaining voltage signal across a capacitive load requires increasing current as the frequency of the voltage signal increases. In many applications, it is common to test devices using sinusoidal tones of constant peak voltage at various frequencies. This may pose a challenge to amplifiers driving capacitive loads when high-frequency sinusoidal tones are tested, as the current demands from the amplifier at such frequencies may cause excessive heating in the amplifier, leading to damage. Even in normal usage, for example when playing audio content to a piezoelectric transducer, high-frequency content may be present (e.g., cymbal crashes and/or synthesized sounds in music content) that may cause excessive amplifier heating.